I use flux from a long time. It's a good software. But, I have the same problem with my news laptop Lenovo Idepad with Intel iris graphic.
I had before another lenovo ideapad not being on intel iris is I did not have this problem ...
My windows i'ts a clean install (not pre-installed windows). All my driver are up to date. Windows 10 20H2.
I hope this problem can be corrected ...
PS: Sorry for my little English.
Thanks for your job !